Reverse DNS (PTR) Lookup
Look up the hostname an IP address resolves back to. (Note: this is a genuine PTR lookup, not a list of every domain hosted on that IP — no free source can honestly provide that.)
Frequently Asked Questions
Is the Reverse DNS (PTR) Lookup really free?
Yes — unlimited use, no signup, no credit card. We built these tools to help you audit sites without paying for a data subscription.
Does this tool store or share the URLs I check?
No. Each check runs live and we don't save your input. We keep a short-lived rate-limit counter (by IP) purely to prevent abuse; it is not linked to your results.
How accurate are the results?
This tool reads live, public data directly from the page or domain you enter — it does not rely on a paid third-party database, so it reflects exactly what is publicly visible right now.
A reverse DNS (PTR) lookup takes an IP address and finds the hostname it officially resolves back to — the opposite direction of a normal domain-to-IP lookup. It's genuinely useful for identifying mail servers and verifying infrastructure. One honest caveat up front: this is NOT a way to see every website hosted on a shared IP. That "reverse IP / neighboring domains" feature requires a crawled database of the whole web, which no free tool can honestly provide — so this tool does the real thing (a single PTR lookup), not the fictional version.
How to Use This Tool
Enter an IP address and click Look Up PTR Record. The tool performs a reverse DNS lookup on that IP.
What This Tool Checks
The PTR (pointer) record for the given IP address — the single hostname that IP is configured to resolve back to, if any.
Understanding Your Results
A PTR record commonly reveals the hosting provider or, for mail servers, the mail host's hostname. Many IPs (especially behind CDNs or without reverse DNS configured) return no PTR record at all, which is normal.
How to Fix Common Problems
If you run your own mail server and it has no PTR record (or a generic one), ask your host to set a proper reverse DNS entry matching your sending domain — missing or mismatched reverse DNS is a common reason outbound email gets flagged as spam.
SEO Best Practices
For email deliverability, ensure your sending IP's PTR record matches your sending hostname and that forward and reverse DNS agree. For general research, pair this with DNS and IP lookups rather than expecting it to reveal "sites on the same server."
Example
A reverse lookup on a mail server IP returns "mail.examplehost.com," confirming which provider handles that mail — whereas a lookup on a Cloudflare IP typically returns a generic Cloudflare hostname or nothing.
Common Mistakes to Avoid
Don't expect this to list other domains on the same IP — that's a fundamentally different (and paid, index-based) capability, and any free tool claiming to do it comprehensively is guessing. Don't worry if a normal website IP has no PTR record; it's not required for web hosting.
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